Fix up the tests I added for string exceptions to be skipped when exceptions are disabled

llvm-svn: 258279

libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_iter_iter.pass.cpp

@@ -990,6 +990,7 @@ int main()
     test8<S>();
     }
 #endif
+#ifndef TEST_HAS_NO_EXCEPTIONS
 	{ // test iterator operations that throw
     typedef std::string S;
     typedef ThrowingIterator<char> TIter;
@@ -1003,4 +1004,5 @@ int main()
     test_exceptions(S("abcdefghijklmnopqrst"), 10, 5, TIter(s, s+10, 5, TIter::TADereference), TIter());
     test_exceptions(S("abcdefghijklmnopqrst"), 10, 5, TIter(s, s+10, 6, TIter::TAComparison), TIter());
 	}
+#endif
 }